They are related, both in the same family (Araceae) but Pothos has leaves that are a tad bit thicker than the Philodendron. I too am wondering what the "few different things" are that you've tried to try to make your plant happier. The soil looks quite dry to me which could cause the issues you are experiencing. This Philo requires bright light but no direct sunlight (which will burn the leaves) and the soil should be kept barely moist throughout. I see what appears to be a few rocks on top of the soil and I'd advise removing them. Depending on the type and quality of soil it's planted in, it should be watered thoroughly until water runs out through the drain holes and watered again when the soil feels dry at about 2 inches or so in depth.
~ I'm an old gal who still loves playing in the dirt!
~ Playing in the dirt is my therapy ... and I'm in therapy a lot!
